 // 大屏
 @media screen and (min-width:1200px){
    
}
// 中屏
@media screen and (min-width:992px) and (max-width:1200px){
    
}
 // 小屏
 @media screen and (min-width:768px) and (max-width:992px){
   
 }
 // 移动屏
 @media (max-width:768px) {
    

 }